SFMC sends email to which emailID if more than one email address field is present in Sendable Data Extension

Question

We have a Data Extension with 5000 records in Salesforce Marketing Cloud. There are four fields in the sendable data extension.

Field 1 : CustomerID (text)
Field 2 : Email_1 (Emailaddress)
Field 3 : Email_2 (Emailaddress)
Field 4 : Email_3 (Emailaddress)

Where CustomerID(text) relates to Subscriber on Subscriber key. Email_1, Email_2, Email_3 are all distinct email addresses.

Questions:
1.) If we send an email from Email Studio targeting this data extension, then for each customerID which emailaddress out of Email_1, Email_2, Email_3 will receive the email?

2.) What will be the values present in the All subscribers lists in this case after the emails are sent from Salesforce Marketing Cloud?

Answer 1

@Ester As a best practice, there should be only 1 email address field in the Data Extension, you will get an error message while trying to add more than 1 email address field. However, if you have created the DE with 2 or more email address data type fields then after sending the email to this DE it will show "0" records under tracking. You will have to change the DE fields and keep only 1 Email address field.